Journal of Chemical Technology & Biotechnology

Dyrset, Nils; Selmer‐Olsen, Eirik; Havrevoll, Øystein; Ratnaweera, Harsha; Storrø, Ivar; Birkeland, Stein‐Erik

doi: 10.1002/(SICI)1097-4660(1998110)73:3<175::AID-JCTB936>3.0.CO;2-0pmid: N/A

A continuous process for treatment of dairy wastewater with immobilized lactic acid bacteria has been demonstrated at pilot scale. A strain of Lactobacillus plantarum was selected on the basis of a high conversion rate of lactose at low pH, a high affinity of lactose at low concentrations, and the ability to retain activity for a long time immobilized in alginate beads. Lactose was converted to lactic acid, which lowered the pH and precipitated milk proteins. The proteins were separated together with milk fat by flotation with carboxy methyl cellulose (CMC) or chitosan and gave a solid phase of approx. 10% dry matter (23% protein and 68% fat). The total chemical oxygen demand (CODt) removed varied from 65 to 78% for CMC and 49 to 82% for chitosan. The precipitated material was used as a feed supplement for pigs to provide up to 30% of the total energy intake. No adverse effects on the pig's performance were observed. The energy feed value of the precipitate was estimated to be 2·0 feed units (FUs) per kg dry matter. © 1998 Society of Chemical Industry

Jorio, Hasnaa; Kiared, Karim; Brzezinski, Ryszard; Leroux, Annie; Viel, Guy; Heitz, Michèle

doi: 10.1002/(SICI)1097-4660(1998110)73:3<183::AID-JCTB943>3.0.CO;2-7pmid: N/A

Air biofiltration is now under active consideration for the removal of the volatile organic compounds from air polluted streams. In order to investigate the performance of this newly developed technology, a biofiltration pilot unit was operated for a continuous period of 8 months. The biofilter column was packed with commercially conditioned peat. At start‐up, the filter bed was inoculated with four species of microorganisms. The resulting biofilter was fed with air contaminated with toluene, xylene or a mixture of toluene and xylene. The maximum elimination capacities attained were 165 g m−3 h−1 for toluene, 66 g m−3 h−1 for xylene and 115 g m−3 h−1 for the mixture of toluene and xylene. These specific performances exceed the values published in the technical and commercial literature for similar processes. Xylene isomers were degraded in decreasing order of reactivity, m‐xylene, p‐xylene, o‐xylene. In the case of air polluted with a toluene and xylene mixture, it was noticed that the metabolism of toluene biodegradation was inhibited by the presence of xylene. Characterization of the biofilm microbial populations after several weeks of operation showed that the dominant strains among the isolated culturable strains from the biofilm, even if different from the initially inoculated strains, had at least one physiological property favoring degradation of aromatic organic rings. The performance of the biofilter was found to be dependent on the temperature of the filter media and the pressure drop through the bed. Finally, a steady state mathematical model was tested in order to theoretically describe the experimental results. This model is used to illustrate the operating diffusion and reaction regimes at steady state for the case of each pollutant. © 1998 Society of Chemical Industry

Bódalo Santoyo, Antonio; Bastida Rodríguez, Josefa; Gómez Carrasco, José Luis; Gómez Gómez, Elisa; Alcaraz Rojo, Isabel; Asanza Teruel, María Luisa

doi: 10.1002/(SICI)1097-4660(1998110)73:3<197::AID-JCTB946>3.0.CO;2-Spmid: N/A

The conditions for immobilizing the new L‐aminoacylase‐producing bacterial strain, Pseudomonas sp. BA2, by entrapment in κ‐carrageenan gel, were investigated. The optimal gel concentration and cell load were determined. The addition of CoCl2 and N‐acetyl‐L‐alanine to the immobilizing matrix enhanced L‐aminoacylase activity. The enzymatic properties of immobilized Pseudomonas sp. BA2 were investigated. Enzyme activity in immobilized cells was optimal at a pH of 6·5 using 0·15 mol dm−3 Tris–maleate buffer at 45°C. The presence of 0·7 mmol dm−3 CoCl2 in the enzymatic reaction mixture improved L‐aminoacylase activity. The immobilized cell preparation was used for the production of L‐alanine from N‐acetyl‐DL‐alanine in a batch reactor. Conversions of 100% were obtained using substrate concentrations ranging from 20 to 200 mmol dm−3. The reactor production was 0·74 mol h−1 g cell−1 dm−3 which is noticeably higher than that previously reported in the literature. © 1998 Society of Chemical Industry

Manosroi, Jiradej; Sripalakit, Pattana; Manosroi, Aranya

doi: 10.1002/(SICI)1097-4660(1998110)73:3<203::AID-JCTB947>3.0.CO;2-Ipmid: N/A

Bioconversion of hydrocortisone to prednisolone by free, immobilized and reused immobilized cells of three bacterial strains (Bacillus sphaericus ATCC 13805, Bacillus sphaericus SRP III and Arthrobacter simplex 6946) in an aqueous and a two‐liquid‐phase system using different organic solvents was investigated. The experiments were carried out in a 125 cm3 shake flask at 27±2°C, 220 rpm for 96 h. The contents of prednisolone and hydrocortisone in samples taken at 0, 3, 6, 24, 48, 72, 96 and 144 h were determined by HPLC analysis. The immobilized bacterial cells showed higher prednisolone yield than the free form in an aqueous system. In the two‐phase systems, the butyl acetate to aqueous media ratio of 1: 30 for all three bacterial strains in immobilized forms gave the highest prednisolone yields, at an incubation time of 144 h, of 87·6, 70·6 and 88·3% respectively. For an n‐decane to aqueous ratio of 1: 6, moderate prednisolone yields of 81·8, 47·9 and 71·4% were obtained with shorter incubation times of 72, 96 and 6 h respectively. For cyclohexane and other alcohols, the organisms produced low yields of prednisolone (0–30%). Single reuse of all three immobilized bacterial cells gave a 3–20% lower yield of prednisolone than the non‐reused cells. The increase in hydrocortisone concentration decreased the prednisolone production whereas increasing the n‐decane to aqueous ratio from 1: 6 to 1: 3 caused no significant change in the productivity. © 1998 Society of Chemical Industry

Ocaña, Nuria; Alguacil, Francisco José

doi: 10.1002/(SICI)1097-4660(1998110)73:3<211::AID-JCTB951>3.0.CO;2-Ypmid: N/A

The extraction and stripping reactions of cobalt(II) by Cyanex 301 in Iberfluid diluent from aqueous manganese sulphate solutions has been investigated. The effect of different variables which should influence the extraction‐stripping of cobalt was evaluated, including equilibration time, temperature, organic diluent, extractant concentration, aqueous pH, cobalt loading, strip solution concentration, etc. The number of stages required for the extraction and stripping of cobalt was also evaluated. The results were used to define the conditions for the purification of manganese sulphate solutions. © 1998 Society of Chemical Industry

River, Luis; Aspé, Estrella; Roeckel, Marlene; Martí, M. Cristina

doi: 10.1002/(SICI)1097-4660(1998110)73:3<217::AID-JCTB952>3.0.CO;2-Ppmid: N/A

Although Chile is an important world supplier of marine products, several processing factories have not applied clean technology to improve productivity and reduce the environmental impact of dumping their effluents to coastal seawater. To achieve these goals they need to evaluate their processes and management of effluents. A case‐study of a factory independently processing crustacea, jack mackerel, salmon and fishmeal was carried out. It was found that this type of factory could diminish effluents by saving an average 31·8% in water consumption. Segregation of streams by organic load and flow allowed salvaging of reusable organic matter from the most loaded streams and the design of a combined anaerobic–aerobic treatment for effluents. Final effluents complied with future legal regulations (0·15 kg COD m−3 and 0·05 kg total nitrogen m−3) for their disposal in marine outfalls. Estimated installation costs for the equipment required for organic matter recovery and effluent treatment (primary and secondary) were US$ 37.3 per tonne of product. Recovered organic matter incorporated to the fishmeal process can provide an extra 5·5 tonnes day−1 of the product, which represents savings of at least US$ 308000 per year which could partly pay for the secondary treatment cost of the effluents. © 1998 Society of Chemical Industry

Nguang, Sing Kiong; Chen, Xiao Dong

doi: 10.1002/(SICI)1097-4660(1998110)73:3<227::AID-JCTB954>3.0.CO;2-Gpmid: N/A

This paper has developed a recursive least squares scheme for operating a class of continuous fermentation processes at the optimal steady state productivity. More precisely, the class of continuous fermentation processes under investigation is described by a widely accepted non‐segregated fermentation process model. Based on a recursive least squares algorithm, an on‐line estimation scheme for estimating the optimal set points for feed substrate concentration and dilution rate is developed. Finally, via simulation, it is shown that this on‐line estimation scheme is robust against measurement time (sampling time). © 1998 Society of Chemical Industry

Nguang, Sing Kiong; Chen, Xiao Dong

doi: 10.1002/(SICI)1097-4660(1998110)73:3<233::AID-JCTB955>3.0.CO;2-Epmid: N/A

This paper examines the problem of high frequency multi‐input periodic operation of continuous fermentation process. Based on π‐criterion published prevously, it is shown theoretically that a continuous fermentation process under the operation of simultaneous high frequency periodic change of feed substrate concentration and dilution rate is always superior over the steady state operation except at the optimal feed substrate concentration. This, however, is yet to be confirmed experimentally. Finally, via computer simulations, a good correlation between the simulation and theoretical calculation of the percentage of improvements on the process productivity is revealed. © 1988 Society of Chemical Industry

Matsumoto, Michiaki; Ohtake, Takaaki; Hirata, Makoto; Hano, Tadashi

doi: 10.1002/(SICI)1097-4660(1998110)73:3<237::AID-JCTB956>3.0.CO;2-7pmid: N/A

The extraction rates of amino acids from alkaline aqueous solution into an emulsion liquid membrane containing tri‐n‐octylmethylammonium chloride as a carrier and Paranox 100 as an emulsifier were measured using a stirred transfer cell. The effects of agitation speed (0·33–0·66 rev s−1), amino acid concentrations (0·5–50 mol m−3) and temperature (10–45°C) on the extraction rates were examined. The results were analyzed by a double‐film model. The mass transfer coefficients of amino acids (0·26–1·58×10−5 m s−1) and their complexes (0·60–1·72×10−5 m s−1) were found to correlate well with the hydrophobicities of the amino acids. It was found that the surfactant layer influenced the mass transfer processes of both amino acids in the aqueous film and their complexes in the organic film. The permeation of amino acids with a large hydrophobicity through the emulsion liquid membrane was promoted by both high distribution and larger mass transfer rates. © 1998 Society of Chemical Industry

Ozergin‐Ulgen, Kutlu; Mavituna, Ferda

doi: 10.1002/(SICI)1097-4660(1998110)73:3<243::AID-JCTB957>3.0.CO;2-5pmid: N/A

This paper provides quantitative information on oxygen transfer as well as the kinetic and metabolic parameters related to oxygen uptake in Streptomyces coelicolor A3(2) cultured in a 20 dm3 computer controlled bioreactor using both defined and complex media. It is evident from the literature that production of antibiotics is strongly affected by the dissolved oxygen concentration. Many processes of antibiotic fermentations have been developed to the point at which the microbial oxygen demand exceeds the oxygen transfer capability of the existing fermentation facilities. As a consequence, the oxygen transfer rate has become the rate limiting factor in such processes. It is necessary to know the oxygen kinetic and metabolic parameters of an aerobic fermentation for a successful scale‐up and operational control of the process. In the literature, information concerning the oxygen uptake kinetics of the Streptomyces cultures is scarce despite their industrial importance. This paper, therefore, provides useful quantitative information on oxygen transfer and uptake rates in S. coelicolor cultures. In the defined medium, the total oxygen uptake rates were in the range of 5–6 mmol O2 dm−3 h−1 throughout the active growth phase, the maximum specific oxygen uptake rate was 7·44 mmol O2 g cell−1 h−1, the specific oxygen maintenance demand was 1·88 mmol O2 g cell−1 h−1, and the kLa values were in the range of 40–100 h−1. In the complex medium, however, the kLa values varied in the range of 18–70 h−1. © 1998 Society of Chemical Industry